Is there a better way to get a value from a block in Ruby?

Question

I have been using if yield self[x] to evaluate whether a block returns true or false. I need to make the block optional, and I see suggestions to do yield if block_given? . How can I combine these two lines?

Answer 1

Have you tried this?

if block_given? && yield(self[x])
  # ...
end

This condition will always fail when no block is given, ie whatever is in place of # ... won't be evaluated. If you want the condition to succeed if no block is given, do this instead:

if !block_given? || yield(self[x])
  # ...
end

Or this, although I think it's harder to read:

unless block_given? && !yield(self[x])
  # ...
end

Answer 2

Try:

if block_given?
   if yield self[x]
      # Do something....
   end
end

Answer 3

You can append a condition to the entire if block:

if yield self[x]
  # do something...
end if block_given?